IMBRAT’Z MULTIMEDIA

In 3D game animation, the character model that is applied to a bone structure is called a skin. The skin should be one combined object with no overlapping parts. You can think of the skin as a glove that is placed over a hand. The glove doesn’t move when it is off the hand, but when the fingers are moved underneath, the glove moves and bends along with the fingers. If there are any holes in the glove, they get stretched open as the fingers move. The same works for a skin over a bone structure.

Skinning a character
Character models typically are created one part at a time, but to make a model into a skin, you need to combine all parts into a single object. If the model consists of any groups, you should dissolve these groups. Objects still can be attached to the skin, but all parts of the skin that move with the bones need to be able to bend and flex.

After a skin is attached to a skeleton, the second part of skinning is to make sure that the skin deforms well when the bones are moved. Each bone has an influence volume that defines the portions of the skin that moves with the bone. If these influence volumes are incorrect, then the skin can deform unrealistically when the bone is moved.

For example, if the influence volume for the upper arm includes part of the side of the character, then rotating the upper arm pulls the character’s side out as the arm is raised, causing a funny-looking bump. To control these deformations, you can precisely control the influence volume. Attaching a skin to a skeleton

After a bone structure is created, it can be attached to the character skin that has already been created.

Some software programs make this a separate step, and others simply require that the bones be positioned within the skin.

Follow these steps to attach a skin to a bone structure in Maya:

1. Choose File –> Open Scene, and open the IK enabled.mb file.

This file is the same file that was saved at the end of the preceding example. Be sure to move the bones back into place before attaching the skin.

2. Select the character model, press and hold the Shift key, and select the pelvis bone. Then choose the Skin –> Bind Skin –> Smooth Bind menu command.

The skin is now attached to the bone structure, so moving any of the bones moves the character model with the bone.

3. Select the ankle joint with the IK chain attached, and move the ankle forward in the Front view. Then select and rotate one of the arms about its upper arm joint.

With the skin binding in place, the character model moves along with the bone movements.

4. Select the File –> Save Scene As menu command, and save the file. Close the file when you are finished.

Setting a bone’s influence
Surrounding each bone is an influence volume (called an envelope in several animation packages) that you can control. The skin that is within this volume moves along with the underlying bone, and the skin that is included in overlapping influence volumes are the areas of the skin where the bending is most extreme, such as at the elbow.

The influence volume is initially set to surround each bone, and the closer the bone matches the skin for each body part, the more accurate the influence volumes are. If any portion of the skin isn’t included within any influence area, then that portion of the skin is left behind when its bones are moved.

Influence volumes can be altered using controls to increase their radius on either end of the bone.

Another way to control which skin parts deform with the underlying bone is to paint the skin vertices using a paint brush. Select a bone and then paint the weight. Different colors depict the skin vertices’ influence. It is important to have a gradual change between skin influences so that the skin moves realistically.

Adding deformations to create muscle bulges
Another aspect of working with the skin object is that you can define deformations based on bone positions. This provides a way to make muscles bulge. For example, deforming the bicep muscle to bulge when the angle between upper and lower arm bones is shortened is a realistic deformation that you’d expect from a realistic character.

Both applications to be 64-bit capable
By Frank Moldstad
 

Maya 8 box
Now that both 3ds Max and Maya are under one roof, it might appear that Autodesk is coordinating their upgrades – at least that’s what it did this week at SIGGRAPH with the announcements of Maya 8 and 3ds Max 9.

 

But  in reality, Maya 8 is shipping in August, while 3ds Max is due in October. The two professional 3D animation applications are now both 64-bit ready for Windows (and Linux for Maya), with 32-bit compatibility for users not on 64-bit platforms, including OSX for Maya. Both programs have also been optimized for large datasets, one of the most crucial features for high-end film, broadcast and game users. Each program also contains numerous improvements, in areas such as productivity, pipeline efficiency, rendering and file exchange capabilities with other programs.

The latter is one of the advantages of Autodesk owning both programs, plus other assets which came to it in the Alias purchase last year. One of those was the FBX plugin, which has now been upgraded for tighter integration between Maya, 3ds Max and MotionBuilder. The new version features interchangeable geometry between Maya and 3ds Max. In addition, render layers can be exported to Autodesk’s Toxik database.

 

There are number of new high-performance features in both applications. Maya 8, the first upgrade out of the gate, introduces scalable multithreading, to take advantage of all processing power when performing skinning, draw tessellation, and subdivided polygon proxy mesh operations. It also features new API extensions for better data management with multiple 2D and 3D packages in a  pipeline. And, not only is there support for 64-bit computing in Maya 8, there are also a number of 64-bit plugins available from  third-party developers in the Autodesk Developer Network (ADN) Sparks program (see below).

Several welcome additions in the area of rendering debut in Maya 8. First, it now uses the mental ray 3.5 core, which has been optimized for better rendering performance and memory usage — and there’s support for interactive viewing of both native and custom mental ray shaders. There’s also the new option to override the Maya viewports with a proprietary or third-party plug-in renderer, for reviewing scenes as they will appear in the target renderer.

Maya 8 also offers intriguing new modeling and texturing enhancements, such as the Transfer Polygon Attributes feature. This makes it possible to transfer UV, color per vertex (CPV) and vertex position information between surface meshes of differing topologies. If an artist is working with two versions of an object of a character, one hi-res and one lo-res, existing UV sets can be transferred if they’re already laid out on the lo-res model. Among the other new tools are a Polygon bridge, multiple edge loop insertion capabilities, and an enhanced UV layout. New workflows include the ability to interactively create, position, and scale primitives in a single operation.

A new Geometry Caching feature bowing in Maya 8 is for caching deformations on polygon, NURBS and subdivision surface geometry. This speeds up both playback and scene rendering. Users can also blend vertex animations together — creating a new animation — in the Trax Editor.

New caching options in Maya 8 apply to deformations on polygon, NURBS (including curves), and subdivision surface geometry.

Meanwhile, over in the 3ds Max camp, there are new tools for lighting, shading, rig building, and modeling. 3ds Max 9 also features the mental ray 3.5 core, and users with big rendering jobs will appreciate Point cache 2, which speeds up the baking of mesh deformations into a file for faster rendering.

Riggers can take advantage of a new layered blending system for custom rigs and controllers in 3ds Max 9. It’s also now possible to save and load XAF files onto bipeds, which makes it easier to transfer information to and from custom rigs.

Workflow improvements include new viewport functionality, such as faster feedback from the Wireframe and edge display tools. The ability to style hair in the viewport is also new, one of several enhancements to hair and cloth functionality. Version 9 also has improved file referencing and asset tracking.

As with Maya, there are also a number of 64-bit plugins available for 3ds Max from third-party developers in the Autodesk Developer Network (ADN) Sparks program. A partnership with HP and Intel provided 64-bit HP xw4300 workstations to a number of ADN Sparks developers in order to port plug-ins in time for the launches of both 3ds Max 9 and Maya 8.

Following is the most recent list of 64-bit plugins created by the ADN Sparks developers for 3ds Max 9 and Maya 8:

3dAliens (www.3daliens.com): glu3D
Archvision (www.archvision.com): RPC plug-ins and content
Axceleon, Inc (www.axceleon.com/3d): EnFuzion
Bionatics (www.bionatics.com): natFX and EASYnat
Boomer Labs (www.boomerlabs.com): MAX2AE
Boris FX (www.borisfx.com): Final Effects Complete
Cebas (www.cebas.com): finalRender
Chaos (www. chaosgroup.com): V-Ray
Character Animation Technologies (www.catoolkit.com): Character Animation toolkit
Cubicspace (www.cubicspace.com): rtre (real time rendering)
Frantic Films Corporation (www.franticfilms.com): Deadline render farm management system
Itoo (www.itoosoft.com): Forest Pack plug-ins
Joe Alter, Inc (www.joealter.com): Shave and a Haircut
Npower Software(www.npowersoftware.com): Power Booleans, Power Nurbs, Power Solids
Okino Computer Graphics (www.okino.com): Polytrans
Orbaz (www.orbaz.com): Particle Flow Tools
Pipeline FX(www.pipelinefx.com): Qube!
Pixar (www.pixar.com): RenderMan
Rad Game Tools (www.radgametools.com): Granny 3D
Right Hemisphere (www.righthemisphere.com): Deep Paint 3D
Sensable (www.sensable.com): Claytools
Size 8 Software (www.size8software.com): clothFX
Syflex LLC (www.syflex.com): Syflex Cloth
T-Splines LLC (www.tsplines.com): T-Splines Plug-in
The English language version of 3ds Max 9 will be available in October 2006, with other languages to follow. Its suggested list price is $3,495, and the upgrade from 3ds Max 8 to 3ds Max 9 is US $795.

Maya 8 also ships in English first, with availability scheduled for August 2006. It carries a suggested list price of $1,999 US for Maya Complete (standalone) and $6,999 US for Maya Unlimited (standalone). Upgrading from Maya 7 Complete to Maya 8 Complete is US $899, and from Maya 7 Unlimited to Maya 8 Unlimited is US $1,249.

DISCREET JUST SHIPPED a new version of 3ds max–version 7. It offers significant new features and, according to Discreet, is more stable. Good news for 3ds max 6 users is that plug-ins for that version remain compatible with this release.

Speaking of plug-ins, Character Studio 4 is now included with 3ds max at no extra charge. The Mental Ray 3.3 subsurface scattering shader now incorporates photometric lighting and includes specialized versions designed specifically to handle skin.

Among 3ds max 7’s new features, several stand out as significant either in terms of new functionality or in making daily operations easier. The paint deformation tool is sure to be a popular addition. It allows users to deform poly objects using an intuitive brush interface. It handles push, pull, relax, and revert operations with full support for soft selections. Brush controls include extensive falloff control, and pressure sensitivity is supported for brush strength and size for those who have pressure-sensitive tablets such as the Wacom. This tool makes adjustments and refinements of poly objects quick and easy.

Normal mapping tools provide a way for visualization professionals to build detailed high-resolution meshes and then apply normal maps to low-resolution models. These normal maps can be rendered with MentalRay and the native Scanline renderer. This approach provides ultimate detail at render time, but allows the user to work with extremely low resolution in the viewport. The lower geometry count enables users to work more quickly in a scene without losing detail.

The TurboSmooth modifier in this release is a new modifier based on MeshSmooth, but with much of the esoteric functionality removed. TurboSmooth is extremely fast because it focuses on what users generally require from smoothing. MeshSmooth is still available if users need any of its features.

3ds max 7’s Highlight Seams capabilities makes it easy to spot discontinuities in the mapping on a model–sure to be a very useful aid in day-to-day work.

I did some preliminary, not-for-publication tests with 3ds max 7, and it does seem speedy. Especially noticeable was an increase in performance with the DirectX driver, which in our initial tests proved to be markedly faster than the OpenGL implementation. The MaxBench4 benchmark, which Cadalyst Labs uses for testing graphics hardware and workstations, ran without a hitch on this release.

3ds max 7 is available for a suggested retail price of $3,495. Upgrades from previous versions are $795 from 3ds max 6, $1,295 from 3ds max 5, and $1,495 from 3ds max 4. As with previous releases, a subscription service is available for $440 per year. In the past, the subscription has provided significant additional functionality for the base product.

There’s obviously a lot more to 3ds max 7 than I can possibly cover in a brief review such as this. Take a closer look at 3ds max on Discreet’s Web site (www.discreet.com).–R.L.